Conventionally, in a case where an apparatus having an image forming function (hereinafter referred to as an image forming apparatus), e.g., a copying machine, printer, facsimile, multi-function apparatus and so on, is connected to a computer network (hereinafter simply referred to as a network) such as a local area network (LAN), an image forming apparatus having network connection means, e.g., a network interface or the like, and an image forming apparatus not having network connection means employ different connection methods.
FIG. 10 is a view of a LAN structure, shown as an example of a network, connecting an image forming apparatus including a network interface and an image forming apparatus not including (or incapable of including) a network interface.
Referring to FIG. 10, reference numeral 5001 denotes a LAN; 5002, an image forming apparatus not having a network interface; 5003, a printer server which enables the image forming apparatus 5002 to connect to the LAN 5001 to serve as a network printer; 5004, a conventional interface used for local connection, typically exemplified by IEEE 1284 (so-called parallel interface); 5005, a communication cable serving as a communication medium of the interface 5004; 5006, a network interface for connecting to the LAN 5001; 5007, an image forming apparatus having a network interface directly connectable to the LAN 5001; 5008, a network interface connecting the image forming apparatus 5007 to the LAN 5001; and 5009, a terminal apparatus connected to the LAN.
Although not shown in the drawing, generally plural terminal apparatuses 5009 are connected to the LAN 5001 as a printing client or a controller of other apparatuses.
The image forming apparatus 5002, which does not have means to connect to the LAN 5001, generally employs the printer server 5003 to communicate with the terminal apparatus 5009 which is connected to the LAN 5001. More specifically, the printer server 5003, having the interface 5004 that is also included in the image forming apparatus 5002, is connected to the image forming apparatus 5002 through the communication cable 5005. Meanwhile, the printer server 5003 is connected to the LAN 5001 through the network interface 5006. By virtue of the above construction, the image forming apparatus 5002 can perform data communication with the terminal apparatus 5009.
When the terminal apparatus 5009 transmits data (packet data) to the printer server 5003, the data is propagated to the LAN 5001 and captured by the printer server 5003 through the network interface 5006. The processing performed by the printer server 5003 is now described with reference to the flowchart in FIG. 11.
When the printer server 5003 receives the data packet (step S5101), the printer server 5003 determines whether the received data is printing data or control data by analyzing, for instance, the packet header portion (step S5102). When the received data is determined as printing data, portions that are not related to printing processing, e.g., the header or footer added for communication through the LAN, are removed from the data, thereby extracting printing data (step S5103). The printing data, extracted in the foregoing manner, is again formed into a packet having a structure suitable to the conventional interface 5004 of the image forming apparatus 5002 (step S5104), and transmitted to the image forming apparatus 5002 (step S5105). The data packet is transmitted to the image forming apparatus 5002 through the communication cable 5005 and interface 5004. The image forming apparatus 5002 processes the data packet and performs image formation on a printing medium based on contents of the data packet. Accordingly, printing processing instructed by the terminal apparatus 5009 is completed.
Meanwhile, if it is determined at the determination step (step S5102) that the received data is control data, the printer server 5003 interprets the control data (step S5106). The control data is converted to a command system that can be interpreted by the image forming apparatus 5002 (step S5107), and transmitted to the image forming apparatus 5002 (step S5105). The image forming apparatus executes processing in accordance with the received command (e.g., performs on-line or off-line control).
Depending on the printer server, there is a type which extracts printing data (step S5103), interprets a page description language (PDL) included in the printing data and converts it to a language that can be interpreted by the image forming apparatus 5002, then forms the converted data into a packet (step S5104), and transmits the packet to the image forming apparatus 5002 (step S5105).
Next, processing performed by the image forming apparatus 5007, which includes a network interface as means to directly connected to the LAN 5001, is explained with reference to the flowchart in FIG. 12.
The data packet from the terminal apparatus 5009 is transmitted directly to the image forming apparatus 5007. The data packet is propagated to the LAN 5001, and captured by the image forming apparatus 5007 through the network interface 5008.
When the image forming apparatus 5007 receives the data packet (step S5201), the image forming apparatus 5007 determines whether the received data is printing data or control data by analyzing, for instance, the packet header portion (step S5202). When the received data is determined as printing data, portions that are not related to printing processing, e.g., the header or footer added for communication through the LAN 5001, are removed from the data, thereby extracting printing data (step S5203). The printing data, extracted in the foregoing manner, is subjected to raster image processing (RIP) (step S5204). RIP, also called rasterizing processing, is processing for converting a received page description language (PDL) to raster image data. The raster image data, obtained by the conversion processing, is subjected to printing processing (step S5205) for image formation on a printing medium. Accordingly, printing processing instructed by the terminal apparatus 5009 is completed.
Meanwhile, if it is determined at the determination step (step S5202) that the received data is control data, the image forming apparatus 5007 interprets the command (step S5206) and executes processing in accordance with the command (step S5207) (e.g., performs on-line or off-line control).
Depending on the type of image forming apparatus 5007 having a network interface, there is a type incapable of interpreting a printing language such as a PDL. An image forming apparatus of this type does not operate solely as a printer, but has a capability to perform image formation in cooperation with other apparatuses connected to the LAN 5001. For instance, the image forming apparatus receives scanner-read image data directly from a network scanner connected to the LAN 5001, or receives image data encoded in a compression form such as JBIG, then performs RIP on the received data (decoded data if necessary), and executes printing. Such printing processing is executable only with respect to a printing request, which is transmitted from an apparatus capable of directly outputting data in a data format that is printable by the image forming apparatus 5007 specified in advance.
As described above, in order to perform printing, the image forming apparatus 5007, having means for directly connecting to the LAN 5001 and means for interpreting a printing language, interprets the printing data (printing language formed into a data packet), transmitted from a client, with the use of the interpretation means. In other words, the image forming apparatus is incapable of printing the printing data written in a printing language or data format that cannot be interpreted by the interpretation means.
On the contrary, the image forming apparatus 5002, not having means for directly connecting to the LAN 5001, can perform printing processing of various printing data written in various printing languages or data formats, by exchangeably utilizing the printer server 5003 for interpreting different printing languages.
However, in a case where the printer server 5003 is provided, the terminal apparatus 5009 cannot directly acquire from the image forming apparatus 5002 information related to the state and features of the image forming apparatus 5002. Furthermore, the image forming apparatus 5002 cannot voluntarily transmit information related to the state and features to the terminal apparatus 5009.